1. Field of the Invention
The present invention relates to a method of isolating a nucleic acid using a material containing an amino group and a carboxyl group and positively charged at a first pH and to a solid material for isolating a nucleic acid which can be used for the method.
2. Description of the Related Art
Methods of isolating nucleic acids using pH dependent ion exchange matrices are known. For example, U.S. published patent application No. 2001/0018513 describes a method of isolating a nucleic acid using a material containing an ionisable group which is positively charged at a first pH such that it can be bound to the nucleic acid and releasing the nucleic acid at a second pH which is higher than the first pH. Examples of the material containing an ionisable group include N-2-acetamido-2-aminoethanesulfonic acid (ACES), N-2-acetamido-2-imidodiacetic acid (ADA), N-trihydroxymethyl-methyl-2-aminoethanesulfonic acid (TES) and trihydroxymethylaminoethane (Tris), etc. U.S. Pat. No. 6,310,199 describes a method of isolating a nucleic acid using a pH dependent ion exchange, the matrix comprising a silica magnetic particle and a plurality of first ion exchange ligands, each first ion exchange ligand comprising an aromatic hydrocarbon ring, a spacer covalently attached to the aromatic hydrocarbon ring, and a linker comprising a linker alkyl chain attached to the silica magnetic particle at its first end and attached to the spacer at its second end.
However, there is still a need for materials a containing ionisable group which can bind to the nucleic acids at a high speed and have a high efficiency of releasing the nucleic aids when pH is increased, even using the above methods.
Thus, the inventors of the present invention searched for materials which can bind to the nucleic acids at a higher speed to adsorb the nucleic acids more rapidly and have a remarkably high efficiency of releasing the nucleic aids when pH is increased, and discovered bifunctional materials containing both an amino group and a carboxyl group.